modification of TPA

1. Good
Morning

2. Biomechanics and force system
of butterfly arch: A device for three-
dimensional controlling of upper molars
Alireza Nikkerdar
Private Practitioner, Tehran, Iran
Presented by
Dr Sankha Nilay Das
PG 1st Year

3. Contents
Introduction
Background
Biomechanical principles
Clinical indications of butterfly arch
Discussion
Conclusion

4. INTRODUCTION
First introduced by Robert A. Goshgarian in
1972. After that, Burstone and Koenig in 1981
have considered many of the biomechanical
aspects of activating the transpalatal arch.

5. TPA
Transpalatal arch (TPA) or palatal bar (PB) is a
device that has been used for many years in
different clinical situations either with fixed or
removable types; the appliance is usually
made of a stiff stainless steel wire with an
omega loop in center

7. Uses of the TPA
1) Correction of Molar Rotation:-

8. Evaluation of molar position

9. Evaluation of molar position

10. 2)Stabilization and Anchorage
Once the position of molars has been
corrected,the TPA serves as a stabilizing
appliance by connecting the two first
molars with the palatal wire. An
anchorage unit is formed that resists the
mesial movement of the molars.
Its quite useful when elastomeric
chain is used on a continuous arch wire.

11. 3)Molar Distalization

13. 4)Additional Molar Movements
Lingual root torque
Buccal root torque
Expansion
Contraction
Prevents molar extrusion
Encourage molar intrusion

14. Molar Intrusion

15. Activation of TPA
Evaluation of TPA activation

16. Initial activation
1)Rotational/Anteroposterior Adjustment or activation

17. 2)Vertical/Transverse Adjustment or activation

18. Sequence of Activation

19. Subsequent Activation

20. The TPA resists the tendency of the
molars to rotate in a mesial direction
around the lingual roots.
however, this idea has not been confirmed by
new articles.
Zablocki et al. pointed out that the PB
neither preserves the anchorage nor the
vertical dimension during orthodontic
treatment.

21. Kojima and Fukui evaluated the
stress level in periodontal
ligament (PDL) in the presence
and absence of PB; they
observed no difference between
the control group and the group
with PB during space closure
stage.

22. Why???
The reason is quite simple.
The failure of upper lingual
appliances to preserve the
anchorage is because of the
inability to resist against
the forces that apply
perpendicular to its long
axis.

23. Anchorage loss
In a maximum anchorage situation,
anchorage loss happens, more or less due
to the creation of a reactive force as a
result of anterior teeth retraction during
space closure.

24. This appears in two distinct forms…
(1) in first order because of mesial-in rotation of
posterior teeth, especially first molars when the
reactive forces apply from buccal surface
related to the centers of resistance; therefore,
widest part of teeth encroaches the extraction
space

25. (2) In second order, as the consequence
of tip-forward moment that exerts on
posterior anchorage units, these teeth
encounter “dumping effect” that leads to
more anchorage loss.

26. Solution…
a rigid framework with high resistance against
distortion and is introduced here as an
appliance that could preserve the posterior
anchorage with simultaneous controlling of
vertical and transverse dimensions

27. Butterfly arch
0.036″/20 gauge
stainless steel wire
Molar bands
Rigid Framework with its unique design

28. Fabrication

30. Biomechanical principles
The biomechanics of butterfly arch are based
on five principles regarding its unique design:
1. The principle of using tensile strength.
2. The principle of using tongue function.
3. The principle of creating reactive forces.
4. The principle of three-dimensional (3D)
interactions.
5. The principle of using short segments.

31. 1)The principle of using tensile strength
when a mesially directed force exerts on
one end of a PB, the resultant of intrinsic
forces is equal to 0, meaning there is no
axial loading. Therefore, connecting left
and right sides of the dental arch in
molar area do nothing with anchorage
reinforcement at all.

32. In butterfly arch, when a force that tends to
displace the teeth of anchorage units applies,
tension rises in all cross sections of the
connecting oblique wire known as “bracing
unit”. This would create an additional
component to counteract mesially directed
force.

33. Force system of a butterfly arch when a mesially directed force (F)
applies on the left side of the picture dealing with resistance
forces (R) of posterior teeth and bracing element (red segment).
This would create an additional component to counteract
mesially directed force.

34. 2)Principle of using tongue function
A wide pentagonal area, which is called here as
“tongue trapping area” (often with acrylic
coverage), could trap and direct the tongue
pressure during functions (swallowing, speech,
and chewing). the wider part of tongue trapping
area is located behind the center of resistance,
and therefore, perpendicular tongue pressure
against palate creates a high level of force on that
area which tends to tip the crowns of upper first
and second molars distally

35. Tip-back moment created by tongue function on tongue
trapping area regarding center of resistance of the appliance.

36. 3)The principle of 3D interactions
• Interaction of vertical and horizontal dimensions
shows the effect of a force on an
object that is displaced by a drag
force (F) in a distinguished direction
(D) with a constant velocity if we
eliminate the role of friction.
D

37. A condition when a
perpendicular force (Fv)
applies on the moving
object. If we need to
maintain the original
velocity, we have to
increase the drag force to
the extent that overcomes
the additional vertically
directed force.

38. The same story is true for the
butterfly arch when the tongue
presses the tongue trapping area
against palate during function.
This vertical component of tongue
force could affect the
inappropriate reactive mesially
directed force of anterior
retraction and therefore could
enhance anchorage in
anteroposterior plane.

39. Interaction of transverse and
horizontal dimensions
The rigidity of butterfly arch is
considerably high. It is made of stiff
stainless steel wire, and soldered
joints create short segments that
increase total rigidity of the
framework of the appliance
markedly.
If this rigid apparatus encounters
anchorage loss, the diameters have
to be shortened inevitably and
“butterfly wing effect” occurs.

40. Butterfly wing effect.
This effect happens when a butterfly closes its wings and
results in diminution in width. The high rigidity of the arch
withstands this phenomenon because a huge force is needed
to distort the multiplication sign-like framework.

41. 4)The principle of creating reactive forces
Regarding causative factors of anchorage loss,
there are some components to neutralize
mesial-in rotation and mesial tipping of the
first- and second orders, respectively,
so establishing a mechanism for applying
reactive forces in the form of mesial-out and
tip-back moments is essential for anchorage
control.

42. # Mesial-out moment is created by 1-mm preactivation (0.5 mm
each side) with opening of omega loop before placing of the
appliance . This expands the inter-molar width slightly and usually
remains until removing the butterfly arch in finishing stage.
# The tip-back moment is created by tongue pressure against the
tongue trapping area.

43. 5)The principle of using short segments
The essence of accurate
application of butterfly arch is
high rigidity for either
preservation of transverse
dimension or stabilization of the
system and prevention of
distortion.
To preclude long lever arms and huge bending moments at soldering
areas due to tongue function during mastication, we must avoid long
segments as far as possible. Therefore, soldering points all over the
framework are made to increase the total rigidity of the appliance
effectively.

44. Clinical indications of butterfly arch
1. Maximum anchorage cases with/without vertical
discrepancy
2. Open bite correction
3. To treat children with vertical maxillary excess
instead of long-term headgear therapy
4. Full-cusp class II patients undergoing orthodontic
camouflage in which maximum anchorage is
required.
5. Full-cusp class II subdivision cases.

45. Modifications
A modification of butterfly
arch for excellent maintaining
of transverse dimension.
A modification of butterfly
arch in impacted teeth
condition.

46. Discussion
Some conventional appliances that are used for
anchorage reinforcement are as follows: headgear,
TPA, Nance appliance, intra-osseous plates, and
screws.
TPA and Nance appliance are good for tooth
movement and rotation control, but because of
biomechanical weaknesses, as mentioned earlier,
anchorage preservation is compromised.

47. Although butterfly arch possesses
numerous distinct advantages, however,
if anchorage value and PDL stress distribution
of the teeth of reactive unit are the same,
and if an equal activation of right and left
closing loops is performed, the result might be
a mesial movement of whole system as the
effect of a huge reactive force of anchorage
loss without any intervention of bracing units
of butterfly arch. This is usually rare.

48. Conclusion
Mechanical principles were described before, and
they are new and unique and could be used for
3D preservation of upper anchorage teeth
effectively. Expressions such as bracing systems
and units, tongue trapping area, and butterfly
wing effect are special mechanical characteristics
of butterfly arch, and all of them are involved in
3D controlling of posterior anchorage units. The
appliance has different shapes and configurations
in various clinical situations.

49. Review Article

50. Three-Dimensional Control
on Lingually Rolled in Molars
using a 3D Lingual Arch
Sunil Sunny, Denny p Joseph, Neethu Mathew, Roshini Sara Rajan, Eldo
Kurian
Journal of Clinical and Diagnostic Research. 2017 Aug, Vol-11(8)

51. The fixed lingual arches that are used for
mandibular molar uprighting works in two
dimensions, whereas the 3D lingual arch
works in all the three dimensions. The 3D
lingual arch was fabricated from a
0.028”round S.S wire with parts consisting of
an adaptor, activator, friction lock and
extender. The friction lock was inserted into
the vertical stubs welded on the molar bands
of the lingually tipped molar. They provided
greater stability and anchorage to the molars.

52. Case Series

53. A 12-year-old female patient: a) with end on molar
relation on right side; b) lingually tipped mandibular
first molars bilaterally; c,d) posterior scissor bite on
left side and deep bite.

54. Insertion of the 3D Lingual
arch immediately after the
extraction of the second
premolars.
Holding arch with anterior
bite plane in the upper
arch.

55. One month later: a) occlusal picture shows the
correction of lingually tipped molars; (b) left lateral
view showing the correction of scissor bite on left
side.

56. a) Lower arch was bonded along with the 3D lingual
arch; b) removed the 3D lingual arch after the
correction of molar uprighting.

57. Effects of transpalatal arch on molar
movement produced by mesial force:
A finite element simulation
Yukio Kojimaa and Hisao Fukuib
Nagoya, Japan

58. They concluded that TPA had no effect
on the initial movement. In the orthodontic
movement, the TPA had almost no effect,
preserving anchorage for mesial movement.
However, the TPA prevented rotational and
transverse movements of the anchor teeth.

59. Thank
You